adam's needle - Adam's Needle; adam's needle - Popular name of the various species of yucca, also known as bear's grass and Spanish bayonet. They are hand-some plants belonging to the lily family, and natives of America, from the southern United States to Central America. The long, thick, and mostly - rigid sword-shaped leaves are borne in tufts or rosettes, and end usually in a spine, while the edges often bear slender threads. The large, drooping flowers are borne in a dense panicle several feet in length, and are succeeded by three valved pods. The leaves yield fibres from which cloth and cordage are made.